Pavement



' lUNrTED STATES PATENT OFFICE.

FREDRIOK CONNOR ROSS, OF MERCHANTVILLE, NEW JERSEY, ASSIGNOR TO IVAN PROWVATTAIN, OF PHILADELPHIA, PENNSYLVANIA.

PAVEMENT.

SPECIFICATION forming part of Letters Patent No. 399,932, dated March 19, 1889.

A li ti fil d August 10, 1888. Serial No. 282,464. (No specimens.)

To all whom it nuty concern:

Be it known that I, FREDRIOK CONNOR Ross, of Merchantville, in the county of Camden and State of New Jersey, have invented certain new and useful Improvements in Pavements, of which the following is a specification.

The present invention consists in improvements in street and other-pavements in which IO the wearing-surface is composed of natural bituminous sand-rock. This bituminous sandrock is a natural product which is'found in several portions of the United States and elsewhere; and it consists of fine sand or sandstone which is naturally impregnated with bituminous material. Analysis of this natural bituminous rock from different States shows that the rock is composed chiefly of fine sand and hard firm elastic bitumen or asphalt, with a small percentage of heavy oils and mineral impurities. This natural rock is admirably adapted for paving purposes, and has the great advantage of being capable for use without any special treatment affecting its composition. It has been customary to use this bituminous rock for forming the surface of pavements by either crushing the same into a finely-divided condition and then heating the same, or, more usually, by subjecting it in the first instance to suffieient heat, which causes the disintegration of the rock. The disintegrated material, while still hot, is then spread to the proper depth, and is then compacted and smoothed by rollers in the usual manner for treating ordinary asphalt pavements, and the pavement is then ready for use. Pavements thus laid with their surface layers composed of this natural rock, which has undergone no treatment except softening or disintegrating it and then rolling it, have proven to be fully equal and in some respects superior to the Trinidad asphalt pavements, such as are ex tensively laid in the streets of the city of \Vashington. They wear equally well, and are easily repaired, and present a surface which is firm, noiseless, and elastic, and which offers an excellent foothold to horses. The pavements made of this natural bituminous rock possess, however, one serious defect, due

to a lack of cohesiveness in the rock The result is that in warm weather, when subjected to the heat of the sun, the pavements not only soften like the Trinidad asphalt pavements, but they partially disintegrate, giving a crumbling surface. When the surface is thus partly crumbled or disintegrated, it is not only more difficult to travel upon, but it is slightly adhesive, so that it adheres to the hoofs of horses and to Vehicle-wheels.

The object and purpose of the present invention are to remedy this defect in pavements composed of this natural bituminous rock; and the invention consists in adding to the natural materiala small per cent. of rosin. The rosin is incorporated with the bituminous sand-rock when the latter is disintegrated, either by crushing or by heating, prior to laying the same. The rosin itself is crushed into a finely-divided state before being incor- 7o porated with the disintegrated rock. In case the powdered rosin is added to the rock when the latter has been disintegrated by crushing, the resulting mixture should be agitated in any suitable manner, so that the mixture may be homogeneous, .and in such cases the mixture should preferably be heated before laying the same. In case, however, the rock has been disintegrated by heating the same, on the addition of the powdered rosin the latter will commingle itself with the disintegrated rock, so that, ordinarily, no further mixing will be required to render the composition homogeneous other than occurs in the laying of the material. The proportion of rosin to be used depends upon the amount and character of wear to which the pavement will be subjected. From two to ten per cent, or even more, by weight, of the rosin may be used; but in the majority of cases four or five 0 per cent. will be found to give the most satisfactory results. The effect of the incorporation of the rosin with the bituminous rock is to increase the cohesiveness of the rock to a remarkable degree, to bind it together, and at the same time to give a firmer and smoother surface to the pavement without diminishing the elasticity thereof. The rosin causes the natural product to cohere so thoroughly that there is no evidence or sign of disintc- I00 gration or crumbling of the pavement when heated far beyond the maximum degree to which it would ever be heated by the suns rays. By thus incorporating the rosin with the natural rock notonly are all the merits and advantages of the pavements as hitherto made with such rock retained, but the added merits render the pavement one which may be termed perfect.

An important feature of advantage of the natural-rock pavements has been that in repairing the same, or in replacing it when it has been necessary to remove portions for excavating beneath the same, the removed material can be replaced by simply disintegrating it. This advantage is still retained in the pavement in which the rosin is incorporated with the natural bituminous sandrock, it being necessary only to heat the material to a degree approaching the meltingpoint of rosin to effectually disintegrate the material.

The mixed rosin and bituminous rock may be molded into blocks, bricks, or tiles for laying sidewalks, or for roofing or draining purposes, the new material being equally well adapted for these purposes.

I am aware that hitherto rosin has been used as an ingredient in paving compositions, and I make no broad claim to it as such ingredient. In all such prior compositions, however, that I am aware of the compositions are artificial compounds in which various isolated materials are selected and combined to constitute a paving composition, and the resulting composition has hence been of a heterogeneous nature. According to the present invention, however, the basic element of the pavement is a natural rock, being a sandstone naturally impregnated with hard bitumen in such proportions as to'ad'apt it for paving purposes without any special treatment affecting its composition, and I have discovered that by incorporating with it preparatory to laying the pavement rosin in substantially the proportions specified the qualities of the natural material for paving purposes are enhanced in a remarkable and valuable degree.

I claim as my invention- A paving material composed of natural bituminous sand-rock-that is, asandstone or sand naturally impregnated with bitumen insuch proportions as to adapt it for paving purposes without any special treatment affecting its composition-in combination with rosin incorporated therewith, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

FREDRIOK CONNOR ROSS. Witnesses:

H. E. GARSED, O. DUBREE. 

